The U.S. government plans on replacing barriers through 100 miles (161 kilometres) of the southern border in California and Arizona, including through a national monument and a wildlife refuge, according to documents and environmental advocates.

The Department of Homeland Security on Tuesday again waived environmental and dozens of other laws to build more barriers along the U.S.-Mexico border.

Funding will come from the Defence Department following the emergency declaration that President Donald Trump signed this year after Congress refused to approve the amount of border wall funding he requested.

Story continues below advertisement

Barriers will go up at Organ Pipe Cactus National Monument, a vast park named after the unique cactus breed that decorates it, and Cabeza Prieta National Wildlife Refuge, which is largely a designed wilderness home to 275 wildlife species. The government will also build new roads and lighting in those areas in Arizona.

Environmental advocates who have sued to stop the construction of the wall say this latest plan will be detrimental to the wildlife and habitat in those areas.

“The Trump administration just ignored bedrock environmental and public health laws to plow a disastrous border wall through protected, spectacular wildlands,” said Laiken Jordahl, who works on border issues at the Center for Biological Diversity.

The Department of Homeland Security did not immediately respond to a request for comment but has typically not said much about construction plans.

At Organ Pipe Cactus National Monument, row after row of cactuses decorate 516 square miles (1,336-square kilometres) of land that once saw so much drug smuggling that over half the park was closed to the public. But illegal crossings in that area dropped off significantly in the past several years, and the government in 2015 reopened the entire monument for the first time in 12 years.

While Arizona has seen an increase in border crossers over the last year, most are families who turn themselves in to Border Patrol agents. The number of drugs that agents seize in the state has also dropped significantly.

But the government is moving forward with more border infrastructure.

Story continues below advertisement

Story continues below advertisement

The waivers the department issued Tuesday are vague in their description of where and how many miles of fencing will be installed. The Center for Biological Diversity says the plans total about 100 miles (160 kilometres) of southern border in both Arizona and California, near Calexico and Tecate.

In Arizona, construction will focus on four areas of the border and will include the replacement of waist-high fencing meant to stop cars with 18- to 30-foot (9-meter) barriers that will be more efficient at stopping illegal crossings.

The government has already demolished refuge land in the Rio Grande Valley of Texas and construction is set to begin any day. On one section of the Lower Rio Grande Valley National Wildlife Refuge, crews have used heavy construction equipment to destroy a mix of trees, including mesquite, mulberry and hackberry. Those trees protect birds during the ongoing nesting season.

According to plans published last year, the cleared land will be filled in and a concrete wall will be installed, with bollards measuring 18 feet (5.5 metres) installed on top.

After months of public outcry, Congress forbade U.S. Customs and Border Protection from building in the nearby Santa Ana wildlife refuge or the non-profit National Butterfly Center. But it didn’t stop money from going to wall construction in other refuge lands, nor did it stop the government from building in otherwise exempted land due to the emergency declaration, said Marianna Trevino Wright, the butterfly centre’s director.

“They’re going to have to protect us in every single spending bill going forward, and they have to protect us against the state of emergency,” Wright said. “And this administration has made it clear … that they don’t want any exemptions.”

Due to technical reasons, we have temporarily removed commenting from our articles. We hope to have this fixed soon. Thank you for your patience. If you are looking to give feedback on our new site, please send it along to feedback@globeandmail.com. If you want to write a letter to the editor, please forward to letters@globeandmail.com.

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.